Various detachable balloon systems are used for vascular occlusion procedures to treat, for example, sacular aneurysms and sinus fistulas during therapeutic embolization of a peripheral or cerebral blood vessel. A detachable balloon is typically attached to a fluid delivery catheter, inserted through an introducer catheter that is positioned proximal an occlusion site, flow-directed to the occlusion site, and inflated to an expanded state. As the fluid delivery catheter is removed from the inflated balloon, the balloon is sealed closed. To navigate through small, tortuous vessels to an occlusion site, a soft durometer, flexible delivery catheter is required. However, mounting a balloon onto a soft durometer, flexible delivery catheter without premature detachment in the vascular system is problematic.
Occlusion balloon valves are available to admit a soft durometer, flexible delivery catheter therethrough and into the interior of the occlusion balloon without damaging or deforming the delivery catheter. However, the resulting detachment force between the balloon valve and delivery catheter is so low as to establish a high probability of premature detachment in the vascular system. When premature detachment occurs, the balloon moves freely through the vascular system to cause an artificial embolization at an undesirable site, resulting in a possible stroke, heart attack, pulmonary embolism, hemorrhage, or other tissue damage. To increase the detachment force, several unsatisfactory solutions have been suggested. One prior art solution increases the detachment force by increasing the durometer of the delivery catheter to prevent damage and deformation thereof when inserted through and friction-fitted in the balloon valve. However, this higher durometer delivery catheter is unable to navigate smaller, tortuous vessels.
Other prior art solutions include increasing the length of the valve to increase the contact surface area between the valve and delivery catheter or using a tie to close the valve after the balloon is inserted therethrough. However, the longer length valve or the tie end significantly increases the probability of forming life-threatening thrombi about the balloon. In addition, the longer length valve or tie end increases blood flow turbulence and pressure about the occlusion site. This increase in pressure is particularly undesirable in occluded or weak blood vessels such as those requiring embolization procedures. Another disadvantage of this type of balloon closure on detachable balloons is that two or more balloons cannot be positioned in close proximity to each other due to the presence of the tie or long valve extending from the balloon closure.